Graphene is a substance composed of pure carbon, with atoms arranged in a regular hexagonal pattern similar to graphite, but in a one-atom thick sheet. It is very light, with a 1-square-meter sheet weighing only 0.77 milligrams. The structure of graphene is a single planar sheet of sp2-hybrid bonded carbon atoms that are densely packed in a honeycomb crystal lattice. Graphene is most easily visualized as an atomic-scale chicken wire made of carbon atoms and their bonds. The graphene atoms are arranged into a two-dimensional honeycomb structure with the crystalline or “flake” form of graphite consisting of many graphene sheets stacked together.
Graphene is about 100 times stronger than steel; conducts electricity better than copper; and is more flexible than rubber. It is touted as possible replacement for silicon in electronics.
Only identified in 2004, graphene is a single layer of tightly packed carbon atoms making it the thinnest material ever created and offering huge promise for a host of applications from information technology to energy to medicine. Graphene can be made by several methods such as scotch-tape or chemical ex-foliation, chemical vapor deposition (CVD) induced growth, graphite oxide reduction. The two primary methods of production are: chemical exfoliation and graphite oxide reduction. These methods unfortunately only produce small flakes of graphene (usually dispersed in a liquid medium). They also require use of aggressive solvents to break graphene oxide apart from the carbon source (such as graphite) and remove oxygen from graphene oxide to form graphene. Epitaxial Growth on a substrate produces larger graphene sheets (currently able to make up to 40″ square; and works by exposing CH4 and H2 to a substrate (such as copper foil) inside a high temperature furnace. This method requires etching of substrate to remove and transfer the graphene sheet. It is overall, a very costly and time consuming method to produce a large sheet of graphene.
In view of the above, it would be useful to be able to make graphene in a simpler, less costly way. It would also be useful to be able to make graphene directly on a device, thereby eliminating the need for transferring the graphene.